• Nathan P Clark, Daniel M Witt, Loren E Davies, Edward M Saito, Kathleen H McCool, James D Douketis, Kelli R Metz, and Thomas Delate.
• Department of Pharmacy, Kaiser Permanente Colorado, Aurora2Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora.
• JAMA Intern Med. 2015 Jul 1;175(7):1163-8.

ImportanceThe risk of bleeding and recurrent venous thromboembolism (VTE) among patients receiving long-term warfarin sodium therapy for secondary VTE prevention who require temporary interruption of anticoagulant therapy for surgery or invasive diagnostic procedures has not been adequately described.ObjectiveTo describe the rates of clinically relevant bleeding and recurrent VTE among patients in whom warfarin therapy is interrupted for invasive procedures and compare these rates among patients who did and did not receive bridge therapy.Design, Setting, And ParticipantsA retrospective cohort study was conducted at Kaiser Permanente Colorado, an integrated health care delivery system. Patients in whom warfarin therapy was interrupted for invasive diagnostic or surgical procedures between January 1, 2006, and March 31, 2012, were identified via queries of administrative data sets. A total of 1812 procedures in 1178 patients met inclusion criteria. Data on outcomes and exposures were collected between June 1, 2005, and April 30, 2012.ExposuresUse of bridge therapy vs no bridge therapy during warfarin interruption.Main Outcomes And MeasuresThirty-day clinically relevant bleeding, recurrent VTE, and all-cause mortality. Outcomes were verified via manual review of medical records.ResultsAmong the 1178 patients, the mean (SD) age was 66.1 (12.7) years, 830 procedures (45.8%) were in men, and the most common indication for warfarin therapy was deep vein thrombosis (56.3%). Most patients were considered to be at low risk for VTE recurrence at the time of warfarin interruption (1431 procedures [79.0%]) according to the consensus guidelines of the American College of Chest Physicians. Clinically relevant bleeding within 30 days after the procedure in the bridge therapy and non-bridge therapy groups occurred in 15 patients (2.7%) and 2 patients (0.2%), respectively (hazard ratio, 17.2; 95% CI, 3.9-75.1). There was no significant difference in the rate of recurrent VTE between the bridge and non-bridge therapy groups (0 vs 3; P = .56). No deaths occurred in either group.Conclusions And RelevanceBridge therapy was associated with an increased risk of bleeding during warfarin therapy interruption for invasive procedures in patients receiving treatment for a history of VTE and is likely unnecessary for most of these patients. Further research is needed to identify patient- and procedure-related characteristics associated with a high risk of perioperative VTE recurrence during warfarin therapy interruption.

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